A native of Goondiwindi, Queensland, Marsh finest moment as a sprinter was winning the 1995 100 metre IAAF Grand Prix Final in Monaco in a time of 10.13, defeating a field of the world's top sprinters.

Weeks earlier to running 10.13, Marsh led Australia to a silver medal in the 4X100m sprint relay in a national record time of 38.17 at the 1995 IAAF World Championships.

After suffering a ruptured achilles tendon injury during training for the 1996 Atlanta Olympics however, he never returned to such world-class form.

Marsh made the final of the 1993 World Championships 200m event (along with Dean Capobianco, coming 8th with a time of 20.56.

that Australian 4 × 100 m record was actually set in the semi of the Gothenburg (IAAF world champs 1995) meet